There are lifeboat launching appliances from offshore installations, wherein the lifeboat can be launched as a free fall lifeboat or wherein the lifeboat can be launched by falls. The free fall lifeboat launching from an oil rig usually means that the lifeboat is stored on a tilted ramp and can be slid through the ramp into the water under its own weight if a holdback is released. The lifeboat can be recovered usually by a hydraulic davit and a spreader of a wire rope winch. The lifeboat launching from an oil rig by falling under gravity usually means that the lifeboat is stored above sea level and can be lowered into the water by fall of a winch under its own weight if a brake of the winch is released. The lifeboat can be recovered by the opposite operation of the same wire rope winch. In currently used solutions for free-fall based lifeboat launching arrangements, the ramp is a fixed element of the arrangement and it is inseparably connected with the oil rig structure.
The disadvantage of the currently used evacuation arrangements from an oil rig using a lifeboat launched by free fall is that such an arrangement does not provide safe evacuation by lifeboat from an oil rig in any possible circumstances, since launching a lifeboat by free fall is not safe if the water surface is covered with obstacles such as floating ice blocks or construction fragments being a result of an explosion on the oil rig, as it risks damaging or breaking the lifeboat, even more so in conditions of limited visibility or at night.
Despite the fact that currently used free-fall based lifeboat launching arrangements are equipped with a second arrangement that allow for launching the same lifeboat by falls, this method cannot replace a separate lifeboat launching arrangement by fall of a winch. This arrangement is used to recover a lifeboat and it does not meet the requirements and standards for launching lifeboats by fall of a winch, as the lifeboat is moved out of the ramp and lowered into the water using a power supply, and the lifeboat holdback release arrangement consists in manually removing the slings from hooks.
This situation can be currently tackled only by equipping oil rigs with both lifeboat launching arrangements in parallel.
The invention overcomes the indicated drawbacks of the currently used lifeboat launching arrangements by free fall from oil rigs. The arrangement of the invention allows for launching the same lifeboat of the free-fall launching arrangement also by fall of a lifeboat winch in case of an emergency situation and while a power supply is off, which complies with the requirements and standards for this type of launching.
The invention is advantageous in that the arrangement replaces two different separate lifeboat launching arrangements.
The invention is designed to improve the safety of evacuation of people from an oil rig using a lifeboat.